3. Subject Enrollment: The potential study subject's primary care provider will make first contact on behalf of the study and refer interested mothers to study personnel for further information and invitation. Upon enrollment into the study, expectant mothers at approximately 10-14 weeks' gestation will be randomized to receive one of two treatment regimens of vitamin D3. They will be randomized to 1 of 2 groups: (1) Group A: 400 IU vitamin D3/day—Standard dose treatment of placebo (0 IU vitamin D3) plus prenatal vitamin (400 IU/day); or (2) Group B: 4,400 IU/day (4,000 IU/2 gummies/day + 400 IU/day in prenatal). If, after 3 months of vitamin D supplementation, a mother is still frankly vitamin D deficient (less than 15 ng/ml), she will receive open label active vitamin D gummies for the remainder of her pregnancy. To attain equal group numbers (n=150) and balanced numbers by racial/ethnic group (African-American, Caucasian and Hispanic, which represent the predominant groups delivering at MUSC), a stratified block randomization will be used.